mutation-test

Mutation testing identifies weak tests by introducing small, controlled code changes and measuring if the test suite catches them. It exposes redundant or zombie tests that pass despite misbehavior, generating a mutation score and refactoring guidance.

You can run mutation testing by specifying a target file or directory. Use Quick mode for 5 mutations, Standard for 15, or Deep for 30+ mutations. Smart mode auto-detects the target if none is provided.

Yes, mutation testing applies to codebases with test suites and focuses on core modules, critical paths, and pre-release validation to improve reliability. It generates semantic mutations to assess test coverage beyond traditional metrics.

The best way to detect zombie tests is running mutation testing, which introduces controlled code changes to identify tests that pass despite misbehavior. It then provides targeted refactoring guidance to fix these weak tests.

Mutation testing executes mutations in parallel using isolated git worktrees. This isolates each mutation run from your main repository, preventing disruption while assessing test quality across multiple code changes simultaneously.